From d3f84c8b097001e3f31f584b793493cb0033a7ae Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Tue, 13 Feb 2018 09:57:45 +0000 Subject: drm/i915/pmu: Fix PMU enable vs execlists tasklet race Commit 99e48bf98dd0 ("drm/i915: Lock out execlist tasklet while peeking inside for busy-stats") added a tasklet_disable call in busy stats enabling, but we failed to understand that the PMU enable callback runs as an hard IRQ (IPI). Consequence of this is that the PMU enable callback can interrupt the execlists tasklet, and will then deadlock when it calls intel_engine_stats_enable->tasklet_disable. To fix this, I realized it is possible to move the engine stats enablement and disablement to PMU event init and destroy hooks. This allows for much simpler implementation since those hooks run in normal context (can sleep). v2: Extract engine_event_destroy. (Chris Wilson) Signed-off-by: Tvrtko Ursulin Fixes: 99e48bf98dd0 ("drm/i915: Lock out execlist tasklet while peeking inside for busy-stats") Testcase: igt/perf_pmu/enable-race-* Cc: Chris Wilson Cc: Tvrtko Ursulin Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Rodrigo Vivi Cc: intel-gfx@lists.freedesktop.org Reviewed-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/msgid/20180205093448.13877-1-tvrtko.ursulin@linux.intel.com (cherry picked from commit b2f78cda260bc6a1a2d382b1d85a29e69b5b3724) Signed-off-by: Rodrigo Vivi Link: https://patchwork.freedesktop.org/patch/msgid/20180213095747.2424-2-tvrtko.ursulin@linux.intel.com --- drivers/gpu/drm/i915/intel_ringbuffer.h | 14 -------------- 1 file changed, 14 deletions(-) (limited to 'drivers/gpu/drm/i915/intel_ringbuffer.h') diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index c5ff203e42d6..a0e7a6c2a57c 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -366,20 +366,6 @@ struct intel_engine_cs { */ #define I915_ENGINE_SAMPLE_MAX (I915_SAMPLE_SEMA + 1) struct i915_pmu_sample sample[I915_ENGINE_SAMPLE_MAX]; - /** - * @busy_stats: Has enablement of engine stats tracking been - * requested. - */ - bool busy_stats; - /** - * @disable_busy_stats: Work item for busy stats disabling. - * - * Same as with @enable_busy_stats action, with the difference - * that we delay it in case there are rapid enable-disable - * actions, which can happen during tool startup (like perf - * stat). - */ - struct delayed_work disable_busy_stats; } pmu; /* -- cgit v1.2.3